Optical fibers are used in certain missile guidance systems, information being transmitted back and forth from a control station through the optical fiber to the moving missile. The optical fiber is stored on a bobbin in the missile and is paid out as the missile travels toward the target. Because of the high rate of speed of the missile and the consequent high rate at which the fiber is pulled off the bobbin, the fiber must be very carefully wound onto the bobbin to avoid damage to the fiber as it is pulled off the bobbin. It is for this reason that very great care must be taken in winding optical fiber onto a bobbin which is to be used for the transmission of data between a control station and a moving missile.
Equipment has been developed for very precisely measuring the angle at which the fiber is wound onto the bobbin and for traversing the bobbin past an eyelet through which an optical fiber passes to obtain the very precise winding of a layer of fiber on the bobbin. However, a very real difficulty arises when the end of the layer of fiber being wound in one direction is reached and the direction of movement of the bobbin past the eyelet is reversed to wind another layer in the opposite direction. If the winding direction traversal is not done with great precision the end turns in the layer may slough off, resulting in uneven tension when the fiber is pulled from the bobbin. When the fiber is pulled off the bobbin at a very high rate of speed, uneven tension in the fiber can cause the fiber to break. Also, improper reversal of winding direction can result in gaps or spaces between adjacent turns of the fiber at the ends of the layer. A portion of a turn of the fiber layer in the next layer to be wound can slump into this gap and cause the fiber to be pulled off the bobbin at an uneven tension.